JP2006235411A - Method of manufacturing optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing optical elements, with which the thickness of a multilayered film formed on the surface of a substrate is made uniform and optical elements becoming defective products can be reduced. <P>SOLUTION: A sacrifice layer 2 is formed on a substrate 1 for holding (a), and a multilayered film 3 is formed on the sacrifice layer 2 (b), and an adhesive layer 4 is formed on the multilayered film 3 (c), and the multilayered film 3 and the substrate 5 are adhered to each other across the adhesive layer(d), and then cuts 6 of prescribed shapes are provided on a laminated body formed by these steps, from the side of the substrate 5 up to the sacrifice layer 2 (e), and the sacrifice layer 2 is dissolved to obtain an optical element 7 (f). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing an optical element in which a multilayer film is formed on a substrate, such as a filter element used in the field of optical communication.

  For optical elements such as filter elements used in the optical communication field, in order to prevent reflection, to set the transmittance and reflectance for each wavelength to predetermined characteristics, and to set the phase characteristics for each wavelength to predetermined characteristics. In some cases, a multilayer film is formed on the surface of a substrate and given optical characteristics are provided by interference between the films.

  FIG. 2 shows an example of a method for forming such a multilayer film. 2A is a view of the rotary table as viewed from below, and FIG. 2B is an end view of the apparatus at the AA position. A substrate holder 22 is provided in the vacuum chamber 21 and rotates about the rotation shaft 23. A substrate 24 on which a film is formed is concentrically attached to the lower surface of the substrate holder 22, but a monitor substrate 25 is attached to one place where the substrate 24 is attached.

  A target 26 is provided in the lower part of the vacuum chamber 21, and sputtering atoms constituting the film jump out of the target 26 and hit the surfaces of the substrate 24 and the monitor substrate 25 to form a film. Further, a part of the vacuum chamber 21 is provided with windows 27 on the upper and lower surfaces, and the light irradiated from the projector 28 is transmitted through the optical element 24 or the monitor substrate 25 and received by the light receiver 29 to be spectrally separated. The transmittance can be measured. The measurement of the spectral transmittance is performed for film thickness measurement.

  Formation of the multilayer film using the apparatus as shown in FIG. 2 is performed as follows. First, the material of the film, the number of layers, and the thickness of each layer are determined by calculation so that predetermined optical characteristics (reflectance, transmittance, phase characteristics, etc.) can be obtained. When the design is completed in this way, the first layer is first formed. Each time the monitor substrate 25 passes the position of the projector 28 and the light receiver 29, the spectral transmittance is measured and the film thickness is measured.

  In this way, the film formation is continued while measuring the film thickness, and when the measured optical characteristic becomes equal to the reference optical characteristic, the film formation of the first layer is finished. Then, the second layer is formed by changing the material used for sputtering. Thereafter, film formation up to the final film is similarly performed. In general, after that, the substrate 24 on which film formation has been completed is cut to obtain a plurality of optical elements.

  However, when a multilayer film is formed on the surface of the substrate 24 by sputtering as described above, there is a problem that the substrate 24 is warped during the film formation due to the film stress of the multilayer film formed so far. In a normal case, this warp is a warp that protrudes toward the side on which the multilayer film is formed.

  When such a warp occurs, the distance between the surface of the substrate 24 on the film forming side and the target 26 becomes different within the film forming surface of the substrate 24. As a result, the distribution of the film thickness to be formed thereafter. Becomes nonuniform within the film formation surface of the substrate 24. Therefore, there arises a problem that the characteristics of the optical element including the multilayer film and the substrate 24 on which the multilayer film is formed are not predetermined.

  The present invention has been made in view of such circumstances, and an optical element capable of reducing the number of defective optical elements by making the thickness of the multilayer film formed on the surface of the substrate uniform. It is an object to provide a manufacturing method.

  A first means for solving the above problem is a method of manufacturing an optical element including a step of forming a multilayer film on a substrate, wherein a sacrificial layer is formed on a holding substrate, and the sacrificial layer The multilayer film is formed thereon, an adhesive layer is formed on the multilayer film, the multilayer film and the substrate are bonded through the adhesive layer, and then the laminate formed by these steps is formed. The optical element manufacturing method is characterized in that a predetermined shape is cut from the substrate side to the sacrificial layer, and then the sacrificial layer is dissolved to obtain an optical element.

  In this means, since the multilayer film is formed on the holding substrate through the sacrificial layer, if the holding substrate is made strong, warping may occur due to film stress during the film formation. Therefore, a thin film having a uniform thickness can be formed. After the film formation is completed, the substrate is bonded through an adhesive layer.

  The laminated body thus formed is cut into a predetermined shape from the substrate side until it reaches the sacrificial layer, and then the sacrificial layer is dissolved to form a predetermined shape in which a multilayer film is formed on the substrate The optical element is separated from the holding substrate.

  A second means for solving the problem is the first means, in which none of the multilayer film, the adhesive layer, and the substrate is dissolved in a solution for dissolving the sacrificial layer. It is characterized by being.

  In this means, since only the sacrificial layer and the holding substrate are dissolved in the solution, the obtained optical base material is not damaged by the solution. Note that there is no problem even if the holding substrate is formed of a material that does not dissolve in the dissolving solution, and such a substrate is also included in this means.

  A third means for solving the problem is the first means, wherein the adhesive layer is a resin, the substrate is glass or quartz, and the sacrificial layer is a metal that dissolves in an alkali. It is characterized by being.

  Since the multilayer film does not normally dissolve in an alkaline solution, in this means, if an alkaline solution is used as the solution, the sacrificial layer is dissolved without affecting the substrate, the adhesive layer, and the multilayer film, and an optical element is obtained. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical element which can make the film thickness of the multilayer film formed into the surface of a board | substrate uniform thickness, and can reduce the optical element used as a defect product can be provided. .

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a process of an optical element manufacturing method which is an example of an embodiment of the present invention.

  First, an aluminum thin film that is a sacrificial layer 2 is formed on a holding substrate 1 having sufficient strength (a). Although the thickness of the aluminum thin film is 10 nm, an appropriate value can be selected as appropriate. In the following film formation, a sputtering apparatus is used except for the formation of a resin layer as an adhesive, but other usable film formation methods can be arbitrarily selected and used.

Subsequently, a multilayer optical thin film 3 is formed on the sacrificial layer 2 as described in the description of the prior art (b). For example, a total of 181 layers of Nb ₂ O ₅ having a thickness of about 100 to 200 nm and SiO ₂ having a thickness of about 50 to 100 nm are alternately formed to form the multilayer optical thin film 3. The material, thickness, and number of films used for the multilayer optical thin film 3 are determined by optical design so that desired optical characteristics can be obtained.

  Subsequently, an adhesive 4 made of an ultraviolet curable resin is applied on the multilayer optical thin film 3 (c). Subsequently, BK7 glass having a thickness of 0.2 mm to be the substrate 5 is placed thereon, and ultraviolet rays are irradiated through the substrate 5 to cure the adhesive 4 and bond the multilayer optical thin film 3 and the substrate 5 (d). As the substrate 5, quartz or other known materials can be used as appropriate. The adhesive 4 is not particularly limited as long as it can adhere the multilayer optical thin film 3 and the substrate 5 and does not affect the optical characteristics.

  Cuts 6 having a desired shape are made from the substrate 5 side into the laminated body thus formed (e). The depth of the cut may be sufficient to reach the sacrificial layer 2. However, since the thickness of the sacrificial layer 2 is usually thin, as shown in the figure, it reaches the middle of the holding substrate 1. To do.

  Thereafter, when this laminate is immersed in an aqueous sodium hydroxide solution, the aluminum thin film that is the sacrificial layer 2 is dissolved, and the holding substrate 1 is peeled off to obtain the optical element 7 having a desired shape (f).

  Although aluminum is used as the sacrificial layer 2, an appropriate material can be selected as long as at least the multilayer optical thin film 3, the adhesive 4, and the substrate 5 are dissolved in a solution that is difficult to damage. In general, since the multilayer optical thin film 3 and the substrate 5 are made of a material that does not dissolve in alkali, it is appropriate to use a metal that is easily dissolved in alkali as the sacrificial layer 2. The adhesive 4 is also preferably insoluble in a solution that dissolves the sacrificial layer 2. From this point of view, the solution is preferably an alkaline aqueous solution. It is appropriate to use a metal that is easily dissolved in the material.

It is a figure which shows the process of the manufacturing method of the optical element which is an example of embodiment of this invention. It is a figure which shows the example of the method which shows the example of the method of forming a multilayer film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Holding substrate, 2 ... Sacrificial layer, 3 ... Multilayer optical thin film, 4 ... Adhesive, 5 ... Substrate, 6 ... Cut, 7 ... Optical element

Claims (3)

An optical element manufacturing method including a step of forming a multilayer film on a substrate, wherein a sacrificial layer is formed on a holding substrate, the multilayer film is formed on the sacrificial layer, and the multilayer film An adhesive layer is formed on the substrate, and the multilayer film and the substrate are bonded to each other through the adhesive layer, and then the laminate formed by these steps is predetermined until reaching the sacrificial layer from the substrate side. A method of manufacturing an optical element, wherein the optical element is obtained by dissolving the sacrificial layer. 2. The method of manufacturing an optical element according to claim 1, wherein none of the holding substrate, the multilayer film, the adhesive layer, and the substrate is dissolved in a solution for dissolving the sacrificial layer. A method for producing an optical element characterized by the above. 3. The optical element manufacturing method according to claim 2, wherein the adhesive layer is a resin, the substrate is glass or quartz, and the sacrificial layer is a metal dissolved in an alkali. Device manufacturing method.

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